MaplePrimes - Newest Questions

How to find the intersection of two graphs, x,y axes are list

xiao2788 — Thu, 17 May 2012 01:45:52 Z

I have a problem:

Graph a (in blue) and graph c (in red) are plotted, the value of ax,ay and cx, cy are in list.

program as follows:(also in file q3.mw)

with(plots); ax := [13300, 17400, 12500, 20300, 12100, 22100, 11800, 23100, 11600, 23800, 11400, 24300, 11300, 24700, 11200, 25100]; ay := [.2, .2, .3, .3, .4, .4, .5, .5, .6, .6, .7, .7, .8, .8, .9, .9]; cx := [17700,...

problems with assume

Denis — Wed, 16 May 2012 23:06:16 Z

Dear Maple Users,

I'm solving quite a complicated task, so I tried to simplified an example.

There is an equation:

SOL := fsolve(Nz+int(int(StrssCctXY(x, y), x = -(1/2)*b .. (1/2)*b), y = -(1/2)*h .. (1/2)*h) = 0, {C1 = -(1/2)*h .. (1/2)*h})

StrssCctXY(x,y) is piecewise function containing C1 variable, to solve an equation I had to use assumptions on C1 via assume(C1<num1, C1>-num2) command, after that C1 becomes C1~;

over defined problem

farazhedayati — Wed, 16 May 2012 20:02:29 Z

Have to solve and ODE in the domain of [-infnity +infinity ] via specific analytical method but due to some restrictions it could not be solved. In order to solve it, I have separated the domain into [-infinity 0 ] and [0 infinity]. So, I have to add some boundary values at x=0 to the problem. Assuming the solution of the mentioned ODE in [-infinity 0 ] is g(x) and in [0 infinity] is f(x), I added the boundary values of f(0)=g(0)=a and f ' (0)=b and obtained f(x...

best way to visualize a mapping

pgr — Wed, 16 May 2012 11:06:34 Z

hi. i sometimes want to see how a subset A of the complex plane behaves under a certain mapping f. i plot A in red and f(A) in blue into the same plot. no problem so far.

but i also want to see how certain points are mapped to better understand the mapping. in some old maple version (like 5) i hacked that in by running through the plot structure and add green lines from z to f(z) for like every 10th entry to the plot.

now in maple...

plotting the complex plane

pgr — Wed, 16 May 2012 10:56:38 Z

hi. i am regularly plotting subsets of the complex plane. but i have not figured out yet how i can have the vertical axis labeled with i, 2i, 3i, ... instead of 1, 2, 3, ...

how do i do it?

why this error happen and disappear in a same Proc?

ZhuWeihong — Wed, 16 May 2012 07:44:53 Z

this error message hapened,but i try process agin ,this erro disappeared, the proce is perfect, but then it appear agin. is this a bug? i use maple 16.

> restart;
> with(plots);
> with(DEtools);
> pendulums := proc (L, angle, velocity, a, b, n) local i, deq, X, Y, inits, slnnf, ACF1, ACF2, ACF3, ACF4; deq := L*(diff(theta(t), `$`(t, 2)))+(diff(X(t), `$`(t, 2)))*cos(theta(t))+(diff(Y(t), `$`(t, 2))+9.81)*sin(theta(t)) = 0; inits := {theta(0...

Unbelievable Maple 15.00 bug ???

luigidavinci — Tue, 15 May 2012 20:45:14 Z

I think I have come across with what it looks like a very basic bug using the member function. I get the error message: "Error, cannot determine if this expression is true or false: (3) < 100" after the execution of the last line to the next code:

>Test:=Array(1..3,[1,2,3]);
>member(3,Test,'l');
>if l<100 then print("yes"); end if;

am I doing something wrong ?? I even checked the type of the variable 'l' and it is indeed an integer...

Objects in Maple 16

gwpatrick — Tue, 15 May 2012 16:08:19 Z

(1) Does ModuleCopy, when automatically called from Object, really get the a shallow copy of the object

as the first parameter in its parameter list? See below, which is copied directly from ?object,create. The

ModuleCopy has first argument new::Dollar but ModuleApply only passes its two arguments not three. I

couldn't find a reference to this feature in the docs.

different answeres for a unit code !!!

farazhedayati — Tue, 15 May 2012 09:42:16 Z

hey

I have wired problems with maple !!!

I run a code twice, I get 2 different answers !!!

I have uploaded the code ! just run it twicw and see the numerical values of alpha and beta at the end ! new_idea_gf.mw

How do I switch an unknown which was previously set?

wdarrel — Tue, 15 May 2012 06:04:26 Z

In the final line, my output is in the form of tau-c*z. How do I switch the tau-c*z back to

zeta, because I want to integrate T with respect to zeta.

Thank you.

> restart;
> with(plots); 
> U := V(zeta)*exp(I*(k*tau-w*z));
> zeta := tau-c*z; 
> Uz := diff(U, z);
> Utau := diff(U, tau);
> Utautau := diff(Utau, tau);
> P := convert(U, trig);
> 
> A := abs(P)^2;
> B := evalc(A);

fsolve is not working

bjxtju — Tue, 15 May 2012 03:34:46 Z

When I used Maple to solve 3 constants in 3 integral equations, fsolve cannot give me the numerial solutions. It copied the equations and showed me “fsolve（......）”. But if I change the positions of 2terms in the equations (for example a+b is rewritten as b+a), fsolve can give me the numerical solutions for the 3 constants.

In most cases, I donot know the right order and it cannot give me the results. So what is the problem?...

Search in a Matrix

hsadeghi — Mon, 14 May 2012 22:05:43 Z

I'm using Linearalgebra and suppose I have a 10x10 matrix. I want to find the closest element in each column of the matrix to 100. Any idea how to do it?

Wrong Killing vectors using DifferentialGeometry:-Tensor package

cosmicstring — Mon, 14 May 2012 10:42:25 Z

I need to find the Killing vectors of a metric.

I initiate the session as

> restart;
> with(DifferentialGeometry); with(Tensor); with(LieAlgebras);
> DGsetup([t, r, z, phi], M);

and enter my metric as

M > g1 := evalDG(-dt &t dt ...);

I do not have an unknown function in my metric but I have two free parameters (e.g. a and b).

I use

M > K1 := KillingVectors(g1, parameters = [a, b]);

décomposition of partition Sub-Set

chouria ali — Mon, 14 May 2012 09:48:30 Z

if I have two partition Pi and Pi 'I want to know the decomposition of Pi'

solving a simple question (motion of a planet around a fixed star)

MinseoKim — Mon, 14 May 2012 07:47:32 Z

Investigate the motion of a planet around a (fixed) star.

make 3D simulation

investigate the orbitals for diffrent initial conditions. Details and parameters

Help me,Plaese